A photoacoustic imaging method is proposed as a technique for imaging the inside of a subject using acoustic waves (typically, ultrasonic waves). The photoacoustic imaging method is a method for visualizing information related to optical characteristic values inside a subject by using acoustic waves generated by irradiating the subject with pulse laser light.
PTL 1 describes a method for receiving acoustic waves from a subject (a breast) by using a plurality of transducers arranged on a hemisphere surface and generating (reconstructing) three-dimensional image data. FIG. 10 is a schematic diagram showing an appearance of a detector described in PTL 1. FIG. 10 shows a state in which the subject is irradiated with light. On this device, a subject person inserts her breast into the hemispherical detector to which transducers are arranged and the subject person lies on her stomach. A gap between the inserted breast and the transducers is filled with water to perform acoustic matching. When measurement is performed, the detector to which the transducers are arranged rotates step by step and the transducers receive acoustic waves at each position. The rotation axis is an axis passing through the top of the hemisphere and the center of the hemisphere. The detector rotates in this way, so that it is possible to perform measurement as if transducers were present in many directions even when a small number of transducers are used. The breast is inserted to be located near the center of the hemisphere of the detector, and pulse light is irradiated from the top portion of the hemisphere on a rotation axis of the detector.